[Archived]

You may have an aux air tank for marathon it should be drained regular , there are other tanks under coach prime tank wet tank secondary tank and aux air tank those are the prevosts tanks they should be drained at 6000 miles

do not get under coach without having proper jack stands under coach or a pit or wheel lifts !!!!!!!!

[Archived]

Tom,

You should have a Marathon installed aux tank that is a real problem with water and rust. Just search Marathon aux tank and you’ll see posts from myself, Al and Jeff who just did one.

[Peter]

BTom…as we both have the same year bus your Marathon AUX tank is behind the left front fender and then behind a narrow panel. I would at least take a look at it. If its original you can bet its full of rust pieces. Ours was full of junk and when drained would plug up.

The original was 3 + gallon. Grainger has what they advertise 5 gallon but I believe an oversized 4 gallon which is close to the old as I could get. The deal maker was the correct pipe fitting outlets. It fit and works much better now. Unable to find aluminum tank which would be a better choice, believe me I tried.

I posted pictures of tank base change..that turned out not to be a big deal.

[Archived]

Generally speaking all of us have two sources of compressed air, and we have two uses for air.

The main source and use of air is the Prevost chassis. It has the engine driven compressor, a dryer, a “wet” tank, primary and secondary brake air tanks and an accessory tank. Some coaches might have additional tanks. The air dryer element or cannister needs to be changed regularly. I change mine every two years some others change it more frequently. Additionally every time you or someone gets under the coach (such as at the lube intervals of 6000 miles) should drain the tanks in sequence to not only drain any collected moisture, but to verify the operation of protection and check valves.

The Prevost chassis use of air is for brakes, suspension, engine belt tensioners, retarder, door lock, shiutters, etc.

The converter also uses air for a variety of purposes and generally adds an auxiliary compressor. Some such as Marathon add an air tank to supplement the Prevost accessory tank. The auxiliary compressor like the engine driven compressor will add water to the air system, but there are only water traps, not an air dryer so it is especially important to drain the accessory tank(s) and traps frequently, especially if the aux compressor is being used. The frequency is dependent upon humidity and where you are located. High temps with high humidity such as in the south in the summer will create a lot of water condensate and maybe daily draining might be required if the compressor is working a lot. I the bus is parked in arid areas and the compressor doesn’t run much less frequent draining will be required.